| Message ID | 20230826034401.640861-1-liushixin2@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] mm: vmscan: try to reclaim swapcache pages if no swap space | expand |
Liu Shixin <liushixin2@huawei.com> writes: > When spaces of swap devices are exhausted, only file pages can be reclaimed. > But there are still some swapcache pages in anon lru list. This can lead > to a premature out-of-memory. > > This problem can be fixed by checking number of swapcache pages in > can_reclaim_anon_pages(). > > Add a new bit swapcache_only in struct scan_control to skip isolating anon > pages that are not in the swap cache when only swap cache can be reclaimed. Better to describe how you test the patch and test results. > Signed-off-by: Liu Shixin <liushixin2@huawei.com> > --- > include/linux/swap.h | 6 ++++++ > mm/memcontrol.c | 8 ++++++++ > mm/vmscan.c | 29 +++++++++++++++++++++++++++-- > 3 files changed, 41 insertions(+), 2 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 456546443f1f..0318e918bfa4 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -669,6 +669,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_p > } > > extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); > +extern long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg); > extern bool mem_cgroup_swap_full(struct folio *folio); > #else > static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry) > @@ -691,6 +692,11 @@ static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) > return get_nr_swap_pages(); > } > > +static inline long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) > +{ > + return total_swapcache_pages(); > +} > + > static inline bool mem_cgroup_swap_full(struct folio *folio) > { > return vm_swap_full(); > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index e8ca4bdcb03c..c465829db92b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7567,6 +7567,14 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) > return nr_swap_pages; > } > > +long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) > +{ > + if (mem_cgroup_disabled()) > + return total_swapcache_pages(); > + > + return memcg_page_state(memcg, NR_SWAPCACHE); > +} > + > bool mem_cgroup_swap_full(struct folio *folio) > { > struct mem_cgroup *memcg; > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7c33c5b653ef..5cb4adf6642b 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -137,6 +137,9 @@ struct scan_control { > /* Always discard instead of demoting to lower tier memory */ > unsigned int no_demotion:1; > > + /* Swap space is exhausted, only reclaim swapcache for anon LRU */ > + unsigned int swapcache_only:1; > + > /* Allocation order */ > s8 order; > > @@ -613,10 +616,20 @@ static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg, > */ > if (get_nr_swap_pages() > 0) > return true; > + /* Is there any swapcache pages to reclaim? */ > + if (total_swapcache_pages() > 0) { > + sc->swapcache_only = 1; > + return true; > + } > } else { > /* Is the memcg below its swap limit? */ > if (mem_cgroup_get_nr_swap_pages(memcg) > 0) > return true; > + /* Is there any swapcache pages in memcg to reclaim? */ > + if (mem_cgroup_get_nr_swapcache_pages(memcg) > 0) { > + sc->swapcache_only = 1; > + return true; > + } > } > > /* > @@ -2280,6 +2293,19 @@ static bool skip_cma(struct folio *folio, struct scan_control *sc) > } > #endif > > +static bool skip_isolate(struct folio *folio, struct scan_control *sc, > + enum lru_list lru) > +{ > + if (folio_zonenum(folio) > sc->reclaim_idx) > + return true; > + if (skip_cma(folio, sc)) > + return true; > + if (unlikely(sc->swapcache_only && !is_file_lru(lru) && > + !folio_test_swapcache(folio))) Just if (unlikely(sc->swapcache_only && !folio_test_swapcache(folio))) is enough. > + return true; > + return false; > +} > + > /* > * Isolating page from the lruvec to fill in @dst list by nr_to_scan times. > * > @@ -2326,8 +2352,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan, > nr_pages = folio_nr_pages(folio); > total_scan += nr_pages; > > - if (folio_zonenum(folio) > sc->reclaim_idx || > - skip_cma(folio, sc)) { > + if (skip_isolate(folio, sc, lru)) { > nr_skipped[folio_zonenum(folio)] += nr_pages; > move_to = &folios_skipped; > goto move; -- Best Regards, Huang, Ying
On 2023/8/28 9:51, Huang, Ying wrote: > Liu Shixin <liushixin2@huawei.com> writes: > >> When spaces of swap devices are exhausted, only file pages can be reclaimed. >> But there are still some swapcache pages in anon lru list. This can lead >> to a premature out-of-memory. >> >> This problem can be fixed by checking number of swapcache pages in >> can_reclaim_anon_pages(). >> >> Add a new bit swapcache_only in struct scan_control to skip isolating anon >> pages that are not in the swap cache when only swap cache can be reclaimed. > Better to describe how you test the patch and test results. OK, I will add the infomation. > >> Signed-off-by: Liu Shixin <liushixin2@huawei.com> >> --- >> include/linux/swap.h | 6 ++++++ >> mm/memcontrol.c | 8 ++++++++ >> mm/vmscan.c | 29 +++++++++++++++++++++++++++-- >> 3 files changed, 41 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/swap.h b/include/linux/swap.h >> index 456546443f1f..0318e918bfa4 100644 >> --- a/include/linux/swap.h >> +++ b/include/linux/swap.h >> @@ -669,6 +669,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_p >> } >> >> extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); >> +extern long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg); >> extern bool mem_cgroup_swap_full(struct folio *folio); >> #else >> static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry) >> @@ -691,6 +692,11 @@ static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) >> return get_nr_swap_pages(); >> } >> >> +static inline long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) >> +{ >> + return total_swapcache_pages(); >> +} >> + >> static inline bool mem_cgroup_swap_full(struct folio *folio) >> { >> return vm_swap_full(); >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index e8ca4bdcb03c..c465829db92b 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -7567,6 +7567,14 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) >> return nr_swap_pages; >> } >> >> +long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) >> +{ >> + if (mem_cgroup_disabled()) >> + return total_swapcache_pages(); >> + >> + return memcg_page_state(memcg, NR_SWAPCACHE); >> +} >> + >> bool mem_cgroup_swap_full(struct folio *folio) >> { >> struct mem_cgroup *memcg; >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index 7c33c5b653ef..5cb4adf6642b 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -137,6 +137,9 @@ struct scan_control { >> /* Always discard instead of demoting to lower tier memory */ >> unsigned int no_demotion:1; >> >> + /* Swap space is exhausted, only reclaim swapcache for anon LRU */ >> + unsigned int swapcache_only:1; >> + >> /* Allocation order */ >> s8 order; >> >> @@ -613,10 +616,20 @@ static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg, >> */ >> if (get_nr_swap_pages() > 0) >> return true; >> + /* Is there any swapcache pages to reclaim? */ >> + if (total_swapcache_pages() > 0) { >> + sc->swapcache_only = 1; >> + return true; >> + } >> } else { >> /* Is the memcg below its swap limit? */ >> if (mem_cgroup_get_nr_swap_pages(memcg) > 0) >> return true; >> + /* Is there any swapcache pages in memcg to reclaim? */ >> + if (mem_cgroup_get_nr_swapcache_pages(memcg) > 0) { >> + sc->swapcache_only = 1; >> + return true; >> + } >> } >> >> /* >> @@ -2280,6 +2293,19 @@ static bool skip_cma(struct folio *folio, struct scan_control *sc) >> } >> #endif >> >> +static bool skip_isolate(struct folio *folio, struct scan_control *sc, >> + enum lru_list lru) >> +{ >> + if (folio_zonenum(folio) > sc->reclaim_idx) >> + return true; >> + if (skip_cma(folio, sc)) >> + return true; >> + if (unlikely(sc->swapcache_only && !is_file_lru(lru) && >> + !folio_test_swapcache(folio))) > Just > > if (unlikely(sc->swapcache_only && !folio_test_swapcache(folio))) > > is enough. That would results the file pages to be skipped too, but what expected is to skip non-swapcache pages in anon lru list. So I think the condition !is_file_lru(lru) is required. Thanks, > >> + return true; >> + return false; >> +} >> + >> /* >> * Isolating page from the lruvec to fill in @dst list by nr_to_scan times. >> * >> @@ -2326,8 +2352,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan, >> nr_pages = folio_nr_pages(folio); >> total_scan += nr_pages; >> >> - if (folio_zonenum(folio) > sc->reclaim_idx || >> - skip_cma(folio, sc)) { >> + if (skip_isolate(folio, sc, lru)) { >> nr_skipped[folio_zonenum(folio)] += nr_pages; >> move_to = &folios_skipped; >> goto move; > -- > Best Regards, > Huang, Ying > . >
Liu Shixin <liushixin2@huawei.com> writes: > On 2023/8/28 9:51, Huang, Ying wrote: >> Liu Shixin <liushixin2@huawei.com> writes: >> >>> When spaces of swap devices are exhausted, only file pages can be reclaimed. >>> But there are still some swapcache pages in anon lru list. This can lead >>> to a premature out-of-memory. >>> >>> This problem can be fixed by checking number of swapcache pages in >>> can_reclaim_anon_pages(). >>> >>> Add a new bit swapcache_only in struct scan_control to skip isolating anon >>> pages that are not in the swap cache when only swap cache can be reclaimed. >> Better to describe how you test the patch and test results. > OK, I will add the infomation. >> >>> Signed-off-by: Liu Shixin <liushixin2@huawei.com> >>> --- >>> include/linux/swap.h | 6 ++++++ >>> mm/memcontrol.c | 8 ++++++++ >>> mm/vmscan.c | 29 +++++++++++++++++++++++++++-- >>> 3 files changed, 41 insertions(+), 2 deletions(-) >>> >>> diff --git a/include/linux/swap.h b/include/linux/swap.h >>> index 456546443f1f..0318e918bfa4 100644 >>> --- a/include/linux/swap.h >>> +++ b/include/linux/swap.h >>> @@ -669,6 +669,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_p >>> } >>> >>> extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); >>> +extern long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg); >>> extern bool mem_cgroup_swap_full(struct folio *folio); >>> #else >>> static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry) >>> @@ -691,6 +692,11 @@ static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) >>> return get_nr_swap_pages(); >>> } >>> >>> +static inline long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) >>> +{ >>> + return total_swapcache_pages(); >>> +} >>> + >>> static inline bool mem_cgroup_swap_full(struct folio *folio) >>> { >>> return vm_swap_full(); >>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>> index e8ca4bdcb03c..c465829db92b 100644 >>> --- a/mm/memcontrol.c >>> +++ b/mm/memcontrol.c >>> @@ -7567,6 +7567,14 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) >>> return nr_swap_pages; >>> } >>> >>> +long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) >>> +{ >>> + if (mem_cgroup_disabled()) >>> + return total_swapcache_pages(); >>> + >>> + return memcg_page_state(memcg, NR_SWAPCACHE); >>> +} >>> + >>> bool mem_cgroup_swap_full(struct folio *folio) >>> { >>> struct mem_cgroup *memcg; >>> diff --git a/mm/vmscan.c b/mm/vmscan.c >>> index 7c33c5b653ef..5cb4adf6642b 100644 >>> --- a/mm/vmscan.c >>> +++ b/mm/vmscan.c >>> @@ -137,6 +137,9 @@ struct scan_control { >>> /* Always discard instead of demoting to lower tier memory */ >>> unsigned int no_demotion:1; >>> >>> + /* Swap space is exhausted, only reclaim swapcache for anon LRU */ >>> + unsigned int swapcache_only:1; >>> + >>> /* Allocation order */ >>> s8 order; >>> >>> @@ -613,10 +616,20 @@ static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg, >>> */ >>> if (get_nr_swap_pages() > 0) >>> return true; >>> + /* Is there any swapcache pages to reclaim? */ >>> + if (total_swapcache_pages() > 0) { >>> + sc->swapcache_only = 1; >>> + return true; >>> + } >>> } else { >>> /* Is the memcg below its swap limit? */ >>> if (mem_cgroup_get_nr_swap_pages(memcg) > 0) >>> return true; >>> + /* Is there any swapcache pages in memcg to reclaim? */ >>> + if (mem_cgroup_get_nr_swapcache_pages(memcg) > 0) { >>> + sc->swapcache_only = 1; >>> + return true; >>> + } >>> } >>> >>> /* >>> @@ -2280,6 +2293,19 @@ static bool skip_cma(struct folio *folio, struct scan_control *sc) >>> } >>> #endif >>> >>> +static bool skip_isolate(struct folio *folio, struct scan_control *sc, >>> + enum lru_list lru) >>> +{ >>> + if (folio_zonenum(folio) > sc->reclaim_idx) >>> + return true; >>> + if (skip_cma(folio, sc)) >>> + return true; >>> + if (unlikely(sc->swapcache_only && !is_file_lru(lru) && >>> + !folio_test_swapcache(folio))) >> Just >> >> if (unlikely(sc->swapcache_only && !folio_test_swapcache(folio))) >> >> is enough. > That would results the file pages to be skipped too, but what expected is to skip non-swapcache > pages in anon lru list. So I think the condition !is_file_lru(lru) is required. Ah, you are right. -- Best Regards, Huang, Ying >> >>> + return true; >>> + return false; >>> +} >>> + >>> /* >>> * Isolating page from the lruvec to fill in @dst list by nr_to_scan times. >>> * >>> @@ -2326,8 +2352,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan, >>> nr_pages = folio_nr_pages(folio); >>> total_scan += nr_pages; >>> >>> - if (folio_zonenum(folio) > sc->reclaim_idx || >>> - skip_cma(folio, sc)) { >>> + if (skip_isolate(folio, sc, lru)) { >>> nr_skipped[folio_zonenum(folio)] += nr_pages; >>> move_to = &folios_skipped; >>> goto move;
On Fri, Aug 25, 2023 at 7:49 PM Liu Shixin <liushixin2@huawei.com> wrote: > > When spaces of swap devices are exhausted, only file pages can be reclaimed. > But there are still some swapcache pages in anon lru list. This can lead > to a premature out-of-memory. > > This problem can be fixed by checking number of swapcache pages in > can_reclaim_anon_pages(). > > Add a new bit swapcache_only in struct scan_control to skip isolating anon > pages that are not in the swap cache when only swap cache can be reclaimed. > > Signed-off-by: Liu Shixin <liushixin2@huawei.com> I can confirm that with the reproducer I posted on v2 this patch fixes the problem, feel free to add: Tested-by: Yosry Ahmed <yosryahmed@google.com> The code LGTM. I personally prefer that we add NR_SWAPCACHE to memcg1_stats, so that it's obvious that it is used by cgroup v1 code, but perhaps maintainers have opinions against that. > --- > include/linux/swap.h | 6 ++++++ > mm/memcontrol.c | 8 ++++++++ > mm/vmscan.c | 29 +++++++++++++++++++++++++++-- > 3 files changed, 41 insertions(+), 2 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 456546443f1f..0318e918bfa4 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -669,6 +669,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_p > } > > extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); > +extern long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg); > extern bool mem_cgroup_swap_full(struct folio *folio); > #else > static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry) > @@ -691,6 +692,11 @@ static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) > return get_nr_swap_pages(); > } > > +static inline long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) > +{ > + return total_swapcache_pages(); > +} > + > static inline bool mem_cgroup_swap_full(struct folio *folio) > { > return vm_swap_full(); > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index e8ca4bdcb03c..c465829db92b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7567,6 +7567,14 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) > return nr_swap_pages; > } > > +long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) > +{ > + if (mem_cgroup_disabled()) > + return total_swapcache_pages(); > + > + return memcg_page_state(memcg, NR_SWAPCACHE); > +} > + > bool mem_cgroup_swap_full(struct folio *folio) > { > struct mem_cgroup *memcg; > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7c33c5b653ef..5cb4adf6642b 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -137,6 +137,9 @@ struct scan_control { > /* Always discard instead of demoting to lower tier memory */ > unsigned int no_demotion:1; > > + /* Swap space is exhausted, only reclaim swapcache for anon LRU */ > + unsigned int swapcache_only:1; > + > /* Allocation order */ > s8 order; > > @@ -613,10 +616,20 @@ static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg, > */ > if (get_nr_swap_pages() > 0) > return true; > + /* Is there any swapcache pages to reclaim? */ > + if (total_swapcache_pages() > 0) { > + sc->swapcache_only = 1; > + return true; > + } > } else { > /* Is the memcg below its swap limit? */ > if (mem_cgroup_get_nr_swap_pages(memcg) > 0) > return true; > + /* Is there any swapcache pages in memcg to reclaim? */ > + if (mem_cgroup_get_nr_swapcache_pages(memcg) > 0) { > + sc->swapcache_only = 1; > + return true; > + } > } > > /* > @@ -2280,6 +2293,19 @@ static bool skip_cma(struct folio *folio, struct scan_control *sc) > } > #endif > > +static bool skip_isolate(struct folio *folio, struct scan_control *sc, > + enum lru_list lru) > +{ > + if (folio_zonenum(folio) > sc->reclaim_idx) > + return true; > + if (skip_cma(folio, sc)) > + return true; > + if (unlikely(sc->swapcache_only && !is_file_lru(lru) && > + !folio_test_swapcache(folio))) > + return true; > + return false; > +} > + > /* > * Isolating page from the lruvec to fill in @dst list by nr_to_scan times. > * > @@ -2326,8 +2352,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan, > nr_pages = folio_nr_pages(folio); > total_scan += nr_pages; > > - if (folio_zonenum(folio) > sc->reclaim_idx || > - skip_cma(folio, sc)) { > + if (skip_isolate(folio, sc, lru)) { > nr_skipped[folio_zonenum(folio)] += nr_pages; > move_to = &folios_skipped; > goto move; > -- > 2.25.1 >
diff --git a/include/linux/swap.h b/include/linux/swap.h index 456546443f1f..0318e918bfa4 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -669,6 +669,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_p } extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); +extern long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg); extern bool mem_cgroup_swap_full(struct folio *folio); #else static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry) @@ -691,6 +692,11 @@ static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) return get_nr_swap_pages(); } +static inline long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) +{ + return total_swapcache_pages(); +} + static inline bool mem_cgroup_swap_full(struct folio *folio) { return vm_swap_full(); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e8ca4bdcb03c..c465829db92b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -7567,6 +7567,14 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) return nr_swap_pages; } +long mem_cgroup_get_nr_swapcache_pages(struct mem_cgroup *memcg) +{ + if (mem_cgroup_disabled()) + return total_swapcache_pages(); + + return memcg_page_state(memcg, NR_SWAPCACHE); +} + bool mem_cgroup_swap_full(struct folio *folio) { struct mem_cgroup *memcg; diff --git a/mm/vmscan.c b/mm/vmscan.c index 7c33c5b653ef..5cb4adf6642b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -137,6 +137,9 @@ struct scan_control { /* Always discard instead of demoting to lower tier memory */ unsigned int no_demotion:1; + /* Swap space is exhausted, only reclaim swapcache for anon LRU */ + unsigned int swapcache_only:1; + /* Allocation order */ s8 order; @@ -613,10 +616,20 @@ static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg, */ if (get_nr_swap_pages() > 0) return true; + /* Is there any swapcache pages to reclaim? */ + if (total_swapcache_pages() > 0) { + sc->swapcache_only = 1; + return true; + } } else { /* Is the memcg below its swap limit? */ if (mem_cgroup_get_nr_swap_pages(memcg) > 0) return true; + /* Is there any swapcache pages in memcg to reclaim? */ + if (mem_cgroup_get_nr_swapcache_pages(memcg) > 0) { + sc->swapcache_only = 1; + return true; + } } /* @@ -2280,6 +2293,19 @@ static bool skip_cma(struct folio *folio, struct scan_control *sc) } #endif +static bool skip_isolate(struct folio *folio, struct scan_control *sc, + enum lru_list lru) +{ + if (folio_zonenum(folio) > sc->reclaim_idx) + return true; + if (skip_cma(folio, sc)) + return true; + if (unlikely(sc->swapcache_only && !is_file_lru(lru) && + !folio_test_swapcache(folio))) + return true; + return false; +} + /* * Isolating page from the lruvec to fill in @dst list by nr_to_scan times. * @@ -2326,8 +2352,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan, nr_pages = folio_nr_pages(folio); total_scan += nr_pages; - if (folio_zonenum(folio) > sc->reclaim_idx || - skip_cma(folio, sc)) { + if (skip_isolate(folio, sc, lru)) { nr_skipped[folio_zonenum(folio)] += nr_pages; move_to = &folios_skipped; goto move;
When spaces of swap devices are exhausted, only file pages can be reclaimed. But there are still some swapcache pages in anon lru list. This can lead to a premature out-of-memory. This problem can be fixed by checking number of swapcache pages in can_reclaim_anon_pages(). Add a new bit swapcache_only in struct scan_control to skip isolating anon pages that are not in the swap cache when only swap cache can be reclaimed. Signed-off-by: Liu Shixin <liushixin2@huawei.com> --- include/linux/swap.h | 6 ++++++ mm/memcontrol.c | 8 ++++++++ mm/vmscan.c | 29 +++++++++++++++++++++++++++-- 3 files changed, 41 insertions(+), 2 deletions(-)